Which feature can be used to grant read/write access to an Amazon S3 bucket?

The ability to grant read/write access to an Amazon S3 bucket can indeed be achieved through both Access Control Lists (ACLs) and Bucket Policies.

Access Control Lists (ACLs) provide a fine-grained way to manage permissions at the object level within a bucket. They allow users to specify which AWS accounts or groups have access to the bucket and what type of access (read or write) they are granted. For instance, an ACL can be set to allow specific users to read objects or write new objects to the bucket.

On the other hand, Bucket Policies offer a more robust and versatile method to control access at the bucket level. These policies are JSON-based statements that dictate what actions can be performed on the bucket and who can perform them. This includes granting read/write permissions to specific users, groups, or even unauthenticated users. Bucket policies allow for more complex configurations, including conditions like IP address restrictions or requiring certain request headers.

Since both ACLs and Bucket Policies enable the granting of read/write access, the combined capability makes the correct choice clear, highlighting the flexibility and options available for managing access in Amazon S3. Server encryption, while important for data security at rest, does not pertain to access control.